Wood burning stoves, fireplaces, etc., pose a significant environment problem. ("Burning permits possible . . . Senate OKs bill relying first on voluntary efforts to cut wood smoke in area by half by 1995." Sanko J., Rocky Mountain News, Apr. 9, 1991.) There are hundreds of designs and configurations of stoves and fireplaces, and all are operated, more or less, for their esthetics and warmth. Some systems burn the fuel more efficiently than others with respect to heat output and still others with respect to pollution. This is particularly true with pellet stoves.
A pellet stove uses a compressed wood product manufactured from, for example saw dust and wood chips, etc., a waste product from the lumber industry. These pellets, sized in an extruded tubular shape nugget about 1/4 inch diameter and 5/8 inch long, provide an economical, renewable fuel source. As wood burning stoves or fireplaces go, the certified pellet burning stove is certainly the more efficient.
The problem is, that even these existing certified pellet stoves are not as friendly to the environment as they could be. Many of the currently available pellet stoves have heat exchange systems to make the system to be more efficient and a burner to reduce the carbon monoxide output. But they are still polluting and there is still room to more efficiently extract heat from the pellet fuel combustion.
It is necessary that the pellet stove apparatus be extremely sensitive in a burn cycle and, in particular, in a "low" burn where the pellet fuel is subject to high carbon monoxide levels in the exhaust gas. It is extremely difficult to keep the flame hot enough to maintain efficient low carbon monoxide levels, yet at a low fuel consumption rate. This would require a system that had a means to control even the smallest combustion flame maintaining an exact temperature, and a means to extract the greatest ratio possible from the heat generated to be called "overall" a high efficacy system. It is important to understand that all existing pellet fuel stoves are manually adjusted. That is, they are set to a "level" of operation by the user and the stove functions to that preset regardless of the ever changing prevailing conditions, e.g., wind changing pressures on air inlet and exhaust outlet, ambient room temperatures, exhaust gas temperatures, etc. These systems do not continuously adjust for the varying conditions and the result is a hit or miss as to efficiency and it is impossible for these system to achieve continuous clean burning.
It may therefore be seen that it is a problem in the art to provide a heating stove that can operate both at low burn, with low emissions and, have a high heat exchange ratio that is environmentally acceptable and still pleasingly esthetic.